[aldoxime_amine]

Active methylene groups and the carbonyl seem to react with each other nicely. But with no acid catlyst elimination of water is difficult. The bridged reactant (bicyclo compound) has something to do with the water but I am not able to understand its role. Any reference or hint is sufficient.

[gfunk]

You can do a base-catalysed condensation as well.

[azmanam]

I suspect the reaction is merely catalytic in potassium carbonate.  The reaction is probably self-perpetuating.  pKa of diketones can be as low as 9 or so.

In my version, the bridged bicyclic diene doesn't play a role in the water extrusion process.

Do you know what the last step is likely to be?

[aldoxime_amine]

Probably double bond formation b/w the 2 benzenes (the one in conjugation with them)

[english]

For the last step, think Diels-Alder.

[jpg28]

My friend, Justin, and I tried doing the mechanism for the reaction. We were able to generate product through these two steps:

1) Aldol Condensation (2x to remove 2H₂O)
2) [4+2] Cycloaddition (Thermal Conditions) aka Diels-Alder Reaction

My friend suspected the aldol condensation since the product has four less hydrogens and two less oxygen atoms (which can be translated to two less water molecules) than the starting materials. Attached herein is the mechanism. Any comments on it would be highly appreciated. Have a nice day!

[aldoxime_amine]

I believe that may be correct. 

[jpg28]

Thank you very much.

[Squirmy]

Attached herein is the mechanism. Any comments on it would be highly appreciated. Have a nice day!

your drawings are simply beautiful :-)

[jpg28]

your drawings are simply beautiful :-)

Wow. I've never heard that compliment from anybody before, thanks! I get very O.C. with my structures sometimes... That's one of the many reasons why I learned to love and enjoy Organic Chemistry. Though I'm a wee bit inclined to Biochemistry, bottom line is that it is still the Organic Chemistry of Biomolecules. I enjoy both. Again, thank you, Squirmy.